Method for producing resin frame equipped membrane electrode assembly

ABSTRACT

A method for producing a resin frame equipped membrane electrode assembly includes: a first conveyance step of supporting a sheet-shaped member having a cathode and an electrolyte membrane by a resin frame member to which the sheet-shaped member is joined and linearly conveying the supported sheet-shaped member to a pressure bonding device; a second conveyance step of conveying an anode to the pressure bonding device by way of a rotary table; and a pressure bonding step of heating and pressing the cathode and the anode from above and below by the pressure bonding device to thereby integrate the cathode and the anode together.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of application Ser. No. 15/960,623filed on Apr. 24, 2018, the contents of which are incorporated herein byreference.

This application is based upon and claims the benefit of priority fromJapanese Patent Applications No. 2017-090124 filed on Apr. 28, 2017, andNo. 2017-090129 filed on Apr. 28, 2017, the contents all of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a method and apparatus for producing aresin frame equipped membrane electrode assembly including a membraneelectrode assembly and a resin frame member provided on an outerperipheral portion thereof.

Description of the Related Art

In general, a solid polymer electrolyte fuel cell employs a solidpolymer electrolyte membrane. The solid polymer electrolyte membrane isa polymer ion exchange membrane. The fuel cell includes a membraneelectrode assembly (MEA) where an anode is disposed on one surface ofthe solid polymer electrolyte membrane, and a cathode is disposed on theother surface thereof.

The membrane electrode assembly is sandwiched between separators(bipolar plates) to thereby form a power generation cell (unit cell). Apredetermined number of the power generation cells are stacked togetherto thereby form a fuel cell stack. In use, for example, the fuel cellstack is mounted in a vehicle as an in-vehicle fuel cell stack.

In recent years, in an attempt to reduce the usage amount of therelatively expensive solid polymer electrolyte membrane and protect thethin solid polymer electrolyte membrane having low strength, a resinframe equipped MEA incorporating a resin frame member on its outerperiphery has been adopted (see Japanese Laid-Open Patent PublicationNo. 2008-071542 for instance).

SUMMARY OF THE INVENTION

In the process of producing the resin frame equipped MEA, the membraneelectrode assembly and the resin frame member are joined togetherintegrally by hot pressing.

The present invention has been made in relation to the above-describedconventional technique, and an object thereof is to provide a method andapparatus for producing a resin frame equipped membrane electrodeassembly in which it is possible to efficiently produce a resin frameequipped membrane electrode assembly.

To accomplish the object, a first aspect of the present inventionprovides a method for producing a resin frame equipped membraneelectrode assembly, the method including: a first conveyance step ofsupporting, by a resin frame member, a sheet-shaped member including afirst electrode and an electrolyte membrane with the first electrodeprovided on one surface thereof, wherein the sheet-shaped member isjoined to an inner peripheral portion of the resin frame member, andlinearly conveying the supported sheet-shaped member to a pressurebonding device; a second conveyance step of conveying a second electrodeto the pressure bonding device by way of a rotary table; and a pressurebonding step of heating and pressing the first electrode and the secondelectrode from above and below by the pressure bonding device andintegrating the first electrode and the second electrode together.

Preferably, in the first conveyance step, a plurality of thesheet-shaped members are conveyed by a strip-shaped frame membermaterial sheet containing a plurality of the resin frame members.

Preferably, the rotary table has, about an axis of rotation, three ormore workpiece placement portions configured to allow the secondelectrode to be placed thereon.

Preferably, the rotary table includes a workpiece placement portion anda hole adjacent to a lower portion of the workpiece placement portion,the rotary table being configured to rotate about a vertical axis ofrotation; a supporting pad configured to allow the second electrode tobe placed thereon is disposed on the workpiece placement portion; and inthe pressure bonding step, the first electrode and the second electrodeare clamped from above and below by an upper mold and a lower mold ofthe pressure bonding device via the hole.

A second aspect of the present invention provides an apparatus forproducing a resin frame equipped membrane electrode assembly, theapparatus including: a first conveying device configured to support, bya resin frame member, a sheet-shaped member including a first electrodeand an electrolyte membrane with the first electrode provided on onesurface thereof, wherein the sheet-shaped member is joined to an innerperipheral portion of the resin frame member, and linearly convey thesupported sheet-shaped member to a pressure bonding device; a secondconveying device including a rotary table and configured to convey thesecond electrode to the pressure bonding device by the rotary table; andthe pressure bonding device configured to heat and press, from above andbelow, the first electrode conveyed by the first conveying device andthe second electrode conveyed by the second conveying device to therebyintegrate the first electrode and the second electrode together.

Preferably, the rotary table has, about an axis of rotation thereof,three or more workpiece placement portions configured to allow thesecond electrode to be placed thereon.

Preferably, the rotary table includes a workpiece placement portion anda hole adjacent to a lower portion of the workpiece placement portion,the rotary table being configured to rotate about a vertical axis ofrotation; a supporting pad configured to allow the second electrode tobe placed thereon is disposed on the workpiece placement portion; andthe pressure bonding device includes an upper mold and a lower moldconfigured to clamp, and heat and press the first electrode and thesecond electrode from above and below via the hole.

According to the first and second aspects of the present invention, thefirst electrode and the electrolyte membrane are linearly conveyed byway of the resin frame member, while the second electrode is conveyed byway of the rotary table, and the first electrode and the secondelectrode are integrated together by pressure bonding in the pressurebonding device. Thus, it is possible to efficiently produce a resinframe equipped membrane electrode assembly including a membraneelectrode assembly and a resin frame member joined to the outerperipheral portion of the membrane electrode assembly, the membraneelectrode assembly containing the electrolyte membrane, and the firstand second electrodes sandwiching the electrolyte membrane therebetween.

A third aspect of the present invention provides a method for producinga resin frame equipped membrane electrode assembly, the methodincluding: a first joining step of thermocompression-bonding asheet-shaped member including a first electrode and an electrolytemembrane with the first electrode provided on one surface thereof to aresin frame member having an opening and an adhesive layer provided onone surface thereof so that an outer peripheral portion of thesheet-shaped member and an inner peripheral portion of the resin framemember on the one surface are joined together; and a second joining stepof thermocompression-bonding a second electrode to the resin framemember so that an outer peripheral portion of the second electrode andan inner peripheral portion of the resin frame member on another surfacethereof are joined together.

Preferably, a thermocompression temperature in the second joining stepis higher than a thermocompression temperature in the first joiningstep.

Preferably, in the second joining step, the first electrode and thesecond electrode are thermocompression-bonded to each other in theopening with the electrolyte membrane being interposed therebetween.

Preferably, in the first joining step, a portion where the outerperipheral portion of the electrolyte membrane overlaps the innerperipheral portion of the resin frame member is clamped andthermocompression-bonded from above and below using frame-shaped moldsconfigured to conform to a shape of the outer peripheral portion of thefirst electrode.

Preferably, in the first joining step, the electrolyte membrane isthermocompression-bonded to a frame member material sheet containing aplurality of the resin frame members.

Preferably, in the second joining step, thermocompression-bonding isperformed in a state in which the resin frame member joined to thesheet-shaped member is stacked on the second electrode.

According to the third aspect of the present invention, the firstjoining step of thermocompression-bonding the sheet-shaped member havingthe electrolyte membrane and the first electrode to the resin framemember, and the second joining step of thermocompression-bonding theresin frame member to the second electrode are performed, rather thanintegrating the electrolyte membrane, the first electrode, the secondelectrode, and the resin frame member together in a singlethermocompression-bonding process. Thus, it is possible to efficientlyproduce the resin frame equipped membrane electrode assembly includingthe membrane electrode assembly and the resin frame member joined to theouter peripheral portion of the membrane electrode assembly, themembrane electrode assembly containing an electrolyte membrane, and thefirst and second electrodes sandwiching the electrolyte membranetherebetween.

The above and other objects features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which a preferredembodiment of the present invention is shown by way of illustrativeexample.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a power generation cell of afuel cell stack;

FIG. 2 is a cross sectional view taken along line II-II in FIG. 1;

FIG. 3A is a side view of a frame member material sheet being reeled outfrom a roll;

FIG. 3B is a plan view of the frame member material sheet being reeledout from the roll;

FIG. 4 is an explanatory diagram for a first joining step in which afirst sheet-shaped member and a resin frame member are joined together;

FIG. 5 is a schematic view of an apparatus for producing a resin frameequipped membrane electrode assembly according to an embodiment of thepresent invention; and

FIG. 6 is an explanatory diagram for a method for producing the resinframe equipped membrane electrode assembly according to an embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method and apparatus for producing a resin frame equipped membraneelectrode assembly according to the present invention will be describedbelow by showing preferred embodiments and with reference to theaccompanying drawings.

As shown in FIGS. 1 and 2, a power generation cell (fuel cell) 12includes a resin frame equipped membrane electrode assembly 10(hereinafter referred to as a “resin frame equipped MEA 10”), and afirst separator 14 and a second separator 16 provided on both sides ofthe resin frame equipped MEA 10. The power generation cell 12 is, forexample, a laterally elongated (or longitudinally elongated) rectangularsolid polymer fuel cell. A plurality of the power generation cells 12are stacked, for example, in the direction of arrow A (the horizontaldirection) or the direction of arrow C (the gravity direction) to form afuel cell stack 11. The fuel cell stack 11 is mounted as an in-vehiclefuel cell stack, in a fuel cell electric automobile (not shown), forexample.

In the power generation cell 12, the resin frame equipped MEA 10 issandwiched between the first separator 14 and the second separator 16.The first separator 14 and the second separator 16 each have a laterally(or longitudinally) elongated rectangular shape. The first separator 14and the second separator 16 are made of, for example, metal plates suchas steel plates, stainless steel plates, aluminum plates, plated steelplates, or metal plates having anti-corrosive surfaces by surfacetreatment. Alternatively, carbon members may be used as the firstseparator 14 and the second separator 16.

The resin frame equipped MEA 10 includes a membrane electrode assembly10 a (hereinafter referred to as a “MEA 10 a”), and a resin frame member24 joined to an outer peripheral portion of the MEA 10 a so as tocircumferentially extend therearound. The MEA 10 a includes anelectrolyte membrane 18, an anode 20 provided on one surface 18 a of theelectrolyte membrane 18, and a cathode 22 provided on another surface 18b of the electrolyte membrane 18. The anode 20 serves as one of a firstelectrode and a second electrode. The cathode 22 serves as the other ofthe first electrode and the second electrode.

The electrolyte membrane 18 is, for example, a solid polymer electrolytemembrane (cation exchange membrane). The solid polymer electrolytemembrane is formed by impregnating a thin membrane of perfluorosulphonicacid with water, for example. The electrolyte membrane 18 is interposedbetween the anode 20 and the cathode 22. As the electrolyte membrane 18,a fluorine based electrolyte may be used, or alternatively a HC(hydrocarbon) based electrolyte may be used.

The surface size (outer size) of the anode 20 is larger than the surfacesizes (outer sizes) of the electrolyte membrane 18 and the cathode 22.Instead of adopting the above structure, the surface size of the anode20 may be smaller than the surface sizes of the electrolyte membrane 18and the cathode 22.

The anode 20 includes a first electrode catalyst layer 20 a joined tothe one surface 18 a of the electrolyte membrane 18, and a first gasdiffusion layer 20 b stacked on the first electrode catalyst layer 20 a.The surface size of the first electrode catalyst layer 20 a and thesurface size of the first gas diffusion layer 20 b are the same as eachother, and are larger than the surface sizes of the electrolyte membrane18 and the cathode 22.

The cathode 22 includes a second electrode catalyst layer 22 a joined tothe surface 18 b of the electrolyte membrane 18, and a second gasdiffusion layer 22 b stacked on the second electrode catalyst layer 22a. The second electrode catalyst layer 22 a and the second gas diffusionlayer 22 b have the same surface size, and are set to have the samesurface size as that of the electrolyte membrane 18. Thus, an outer end22 e of the cathode 22 and an outer end 18 e of the electrolyte membrane18 are at the same position in the surface direction of the electrolytemembrane 18 (in the direction of arrow C in FIG. 2).

The surface size of the cathode 22 is smaller than the surface size ofthe anode 20. The outer end 22 e of the cathode 22 and the outer end 18e of the electrolyte membrane 18 are positioned inside an outer end 20 eof the anode 20.

The surface size of the cathode 22 may be larger than the surface sizeof the anode 20, and the outer end 22 e of the cathode 22 may bepositioned outside the outer end 20 e of the anode 20. Alternatively,the surface size of the anode 20 and the surface size of the cathode 22may have the same surface size, and the outer end 20 e of the anode 20and the outer end 22 e of the cathode 22 may be at the same position inthe surface direction of the electrolyte membrane 18 (in the directionof arrow C in FIG. 2).

The first electrode catalyst layer 20 a is formed by, for example,uniformly depositing porous carbon particles together with an ionconductive polymer binder on the surface of the first gas diffusionlayer 20 b, while platinum alloy is supported on the porous carbonparticles. The second electrode catalyst layer 22 a is formed by, forexample, uniformly depositing porous carbon particles together with anion conductive polymer binder on the surface of the second gas diffusionlayer 22 b, while platinum alloy is supported on the porous carbonparticles.

Each of the first gas diffusion layer 20 b and the second gas diffusionlayer 22 b comprises a carbon paper or a carbon cloth, etc. The surfacesize of the second gas diffusion layer 22 b is smaller than the surfacesize of the first gas diffusion layer 20 b. The first electrode catalystlayer 20 a and the second electrode catalyst layer 22 a are formedrespectively on both surfaces of the electrolyte membrane 18.

The resin frame member 24 has two frame-shaped sheets having differentthicknesses. Specifically, the resin frame member 24 has a firstframe-shaped sheet 24 a including an inner peripheral portion 24 anjoined to the outer peripheral portion of the MEA 10 a, and a secondframe-shaped sheet 24 b joined to the first frame-shaped sheet 24 a. Thefirst frame-shaped sheet 24 a and the second frame-shaped sheet 24 b arejoined together in the thickness direction by an adhesive layer 24 cmade of adhesive 24 d. The second frame-shaped sheet 24 b is joined tothe outer peripheral portion of the first frame-shaped sheet 24 a. Inthe structure, the outer peripheral portion of the resin frame member 24is thicker than an inner peripheral portion 25 of the resin frame member24. The first frame-shaped sheet 24 a and the second frame-shaped sheet24 b may instead have the same thickness.

The first frame-shaped sheet 24 a and the second frame-shaped sheet 24 bare made of resin material. Exemplary materials of the firstframe-shaped sheet 24 a and the second frame-shaped sheet 24 b includepolyphenylene sulfide (PPS), polyphthalamide (PPA), polyethylenenaphthalate (PEN), polyethersulfone (PES), liquid crystal polymer (LCP),polyvinylidene fluoride (PVDF), silicone resin, fluororesin, modifiedpoly phenylene ether (m-PPE) resin, polyethylene terephthalate (PET),polybutylene terephthalate (PBT), or modified polyolefin, for example.

The inner peripheral portion 25 of the resin frame member 24 (the innerperipheral portion 24 an of the first frame-shaped sheet 24 a) ispositioned between an outer peripheral portion 20 c of the anode 20 andan outer peripheral portion 22 c of the cathode 22. Specifically, theinner peripheral portion 25 of the resin frame member 24 is sandwichedbetween an outer peripheral portion 18 c of the electrolyte membrane 18and the outer peripheral portion 20 c of the anode 20. The innerperipheral portion 25 of the resin frame member 24 and the outerperipheral portion 18 c of the electrolyte membrane 18 are joinedtogether via the adhesive layer 24 c. The inner peripheral portion 25 ofthe resin frame member 24 may instead be sandwiched between theelectrolyte membrane 18 and the cathode 22.

The above-described anode 20 has a step at a position corresponding toan inner end 24 ae of the first frame-shaped sheet 24 a. Specifically,the anode 20 has an inclined area 21 c which is inclined relative to theelectrolyte membrane 18, between an area 21 a contacting the innerperipheral portion 24 an of the first frame-shaped sheet 24 a and anarea 21 b contacting the electrolyte membrane 18. Accordingly, in theinclined area 21 c, the first electrode catalyst layer 20 a and thefirst gas diffusion layer 20 b are inclined relative to the electrolytemembrane 18.

In the anode 20, a surface of the area 21 a that is closer to the firstseparator 14, the area 21 a contacting the inner peripheral portion 24an of the first frame-shaped sheet 24 a, is at a position farther fromthe electrolyte membrane 18 than a surface of the area 21 b that iscloser to the first separator 14, the area 21 b contacting theelectrolyte membrane 18.

On the other hand, the cathode 22 is formed into a flat shape extendingfrom an area 23 b contacting the electrolyte membrane 18 to an area 23 aoverlapping the inner peripheral portion 24 an of the first frame-shapedsheet 24 a. Accordingly, the second electrode catalyst layer 22 a andthe second gas diffusion layer 22 b are parallel with the electrolytemembrane 18 over a region from the area 23 b contacting the electrolytemembrane 18 to the area 23 a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24 a.

As an alternative to the above configuration, the anode 20 may be formedinto a flat shape extending from the area 21 b contacting theelectrolyte membrane 18 to the area 21 a contacting the inner peripheralportion 24 an of the first frame-shaped sheet 24 a, and the cathode 22may have an inclined area inclined relative to the electrolyte membrane18 between the area 23 b contacting the electrolyte membrane 18 and thearea 23 a overlapping the inner peripheral portion 24 an of the firstframe-shaped sheet 24 a.

The second frame-shaped sheet 24 b is joined to the outer peripheralportion of the first frame-shaped sheet 24 a with the adhesive 24 d. Aninner end 24 be of the second frame-shaped sheet 24 b is positionedoutside the inner end 24 ae of the first frame-shaped sheet 24 a (in thedirection away from the MEA 10 a) and positioned outside the outer end20 e of the anode 20 and the outer end 22 e of the cathode 22.

The adhesive layer 24 c is provided over an entire surface 24 as of thefirst frame-shaped sheet 24 a on a side closer to the secondframe-shaped sheet 24 b (cathode side). Thus, the adhesive layer 24 c isprovided on the inner peripheral portion 25 as well. As the adhesive 24d of the adhesive layer 24 c, liquid sealant or hot melt adhesive isprovided, for example. The adhesive 24 d is not limited to liquid orsolid adhesive, and not limited to thermoplastic or thermosettingadhesive, etc.

The resin frame member 24 may also be an integrally molded member, notlimited to a structure formed by joining of the first frame-shaped sheet24 a and the second frame-shaped sheet 24 b via the adhesive layer 24 c.Also, the resin frame member 24 may be of a (substantially flat) shapehaving no step from the inner peripheral portion to the outer peripheralportion, not limited to a stepped shape having a relatively thin innerperipheral portion and a relatively thick outer peripheral portion.

As shown in FIG. 1, at one end of the power generation cell 12 in thedirection of arrow B (the horizontal direction), an oxygen-containinggas supply passage 30 a, a coolant supply passage 32 a, and a fuel gasdischarge passage 34 b are provided. The oxygen-containing gas supplypassage 30 a, the coolant supply passage 32 a, and the fuel gasdischarge passage 34 b extend through the power generation cell 12 inthe stacking direction indicated by the arrow A. The oxygen-containinggas is supplied through the oxygen-containing gas supply passage 30 a,and the coolant is supplied through the coolant supply passage 32 a. Afuel gas such as a hydrogen-containing gas is discharged through thefuel gas discharge passage 34 b. The oxygen-containing gas supplypassage 30 a, the coolant supply passage 32 a, and the fuel gasdischarge passage 34 b are arranged in the direction of arrow C (thevertical direction).

At the other end of the power generation cell 12 in the direction ofarrow B, a fuel gas supply passage 34 a for supplying the fuel gas, acoolant discharge passage 32 b for discharging the coolant, and anoxygen-containing gas discharge passage 30 b for discharging theoxygen-containing gas are provided. The fuel gas supply passage 34 a,the coolant discharge passage 32 b, and the oxygen-containing gasdischarge passage 30 b extend through the power generation cell 12 inthe direction indicated by the arrow A. The fuel gas supply passage 34a, the coolant discharge passage 32 b, and the oxygen-containing gasdischarge passage 30 b are arranged in the direction of arrow C.

The second separator 16 has an oxygen-containing gas flow field 36 onits surface 16 a facing the resin frame equipped MEA 10. Theoxygen-containing gas flow field 36 is connected to theoxygen-containing gas supply passage 30 a and the oxygen-containing gasdischarge passage 30 b. Specifically, the oxygen-containing gas flowfield 36 is formed between the second separator 16 and the resin frameequipped MEA 10. The oxygen-containing gas flow field 36 includes aplurality of straight flow grooves (or wavy flow grooves) extending inthe direction of arrow B.

The first separator 14 has a fuel gas flow field 38 on its surface 14 afacing the resin frame equipped MEA 10. The fuel gas flow field 38 isconnected to the fuel gas supply passage 34 a and the fuel gas dischargepassage 34 b. Specifically, the fuel gas flow field 38 is formed betweenthe first separator 14 and the resin frame equipped MEA 10. The fuel gasflow field 38 includes straight flow grooves (or wavy flow grooves)extending in the direction of arrow B.

A coolant flow field 40 is formed between a surface 14 b of the firstseparator 14 and a surface 16 b of the second separator 16 that areadjacent to each other. The coolant flow field 40 is connected to thecoolant supply passage 32 a and the coolant discharge passage 32 b. Thecoolant flow field 40 extends in the direction of arrow B.

As shown in FIG. 2, a plurality of ridges 39 forming the fuel gas flowfield 38 are provided on the surface 14 a of the first separator 14 (thesurface facing the resin frame equipped MEA 10). The ridge 39 protrudestoward the anode 20 and contacts the anode 20. A plurality of ridges 37forming the oxygen-containing gas flow field 36 are provided on thesurface 16 a of the second separator 16 (the surface facing the resinframe equipped MEA 10). The ridges 37 protrude toward the cathode 22,and contact the cathode 22. The MEA 10 a is sandwiched between theridges 37 and 39.

A first seal line 42 (metal bead seal) extending around the outerperipheral portion of the first separator 14 is provided on the surface14 a of the first separator 14. The first seal line 42 is expandedtoward the resin frame member 24 and contacts the first frame-shapedsheet 24 a (the area overlapping the second frame-shaped sheet 24 b) inan airtight and liquid-tight manner. The first seal line 42 has an outerbead 42 a and an inner bead 42 b provided inside the outer bead 42 a.

The inner bead 42 b is provided around the fuel gas flow field 38, thefuel gas supply passage 34 a, and the fuel gas discharge passage 34 b ina manner that the fuel gas flow field 38 is connected to the fuel gassupply passage 34 a and the fuel gas discharge passage 34 b. Each of thebeads 42 a, 42 b is tapered in cross section toward the front end(toward the resin frame member 24). The front end of each of the beads42 a, 42 b has a flat shape (or may have a curved shape).

A channel 38 a formed between the first separator 14 and the resin framemember 24 is connected to the fuel gas flow field 38 inside the firstseal line 42 (on the MEA 10 a side). Thus, the channel 38 a is suppliedwith fuel gas.

A second seal line 44 (metal bead seal) extending around the outerperipheral portion of the second separator 16 is provided on the surface16 a of the second separator 16. The second seal line 44 is expandedtoward the resin frame member 24 and contacts the second frame-shapedsheet 24 b in an airtight and liquid-tight manner. The first seal line42 and the second seal line 44 face each other across the resin framemember 24. The resin frame member 24 is sandwiched between the firstseal line 42 and the second seal line 44. The second seal line 44 has anouter bead 44 a and an inner bead 44 b provided inside the outer bead 44a.

The inner bead 44 b is provided around the oxygen-containing gas flowfield 36, the oxygen-containing gas supply passage 30 a, and theoxygen-containing gas discharge passage 30 b in a manner that theoxygen-containing gas flow field 36 is connected to theoxygen-containing gas supply passage 30 a and the oxygen-containing gasdischarge passage 30 b. Each of the beads 44 a, 44 b is tapered in crosssection toward the front end (toward the resin frame member 24). Thefront end of each of the beads 44 a, 44 b has a flat shape (or may havea curved shape).

A channel 36 a formed between the second separator 16 and the resinframe member 24 is connected to the oxygen-containing gas flow field 36inside the second seal line 44 (on a side adjacent to the MEA 10 a).Thus, the channel 36 a is supplied with oxygen-containing gas.

Operation of the fuel cell stack 11 including the power generation cell12 thus configured will described below.

As shown in FIG. 1, an oxygen-containing gas is supplied to theoxygen-containing gas supply passage 30 a, and a fuel gas such as ahydrogen-containing gas is supplied to the fuel gas supply passage 34 a.Further, a coolant such as pure water, ethylene glycol, or oil issupplied to the coolant supply passage 32 a.

Thus, the oxygen-containing gas flows from the oxygen-containing gassupply passage 30 a to the oxygen-containing gas flow field 36 of thesecond separator 16, and moves in the direction of arrow B, and theoxygen-containing gas is supplied to the cathode 22 of the MEA 10 a.Meanwhile, the fuel gas flows from the fuel gas supply passage 34 a tothe fuel gas flow field 38 of the first separator 14. The fuel gas movesin the direction of arrow B along the fuel gas flow field 38, and thefuel gas is supplied to the anode 20 of the MEA 10 a.

Consequently, in the MEA 10 a, the oxygen-containing gas supplied to thecathode 22 and the fuel gas supplied to the anode 20 are partiallyconsumed in the second electrode catalyst layer 22 a and the firstelectrode catalyst layer 20 a by electrochemical reactions, therebygenerating electric energy.

Then, in FIG. 1, the oxygen-containing gas after being supplied to andpartially consumed at the cathode 22 is discharged in the direction ofarrow A along the oxygen-containing gas discharge passage 30 b.Likewise, the fuel gas after being supplied to and partially consumed atthe anode 20 is discharged in the direction of arrow A along the fuelgas discharge passage 34 b.

The coolant supplied to the coolant supply passage 32 a flows into thecoolant flow field 40 between the first separator 14 and the secondseparator 16, and then flows in the direction of arrow B. After coolingthe MEA 10 a, the coolant is discharged from the coolant dischargepassage 32 b.

Next, a method for producing the resin frame equipped MEA 10 accordingto the present embodiment will be described below.

The method for producing the resin frame equipped MEA 10 includes: afirst joining step of joining a first sheet-shaped member 56 having anelectrolyte membrane 18 and a first electrode (the cathode 22 in thepresent embodiment), which is one of the electrodes of the resin frameequipped MEA 10, to the resin frame member 24 bythermocompression-bonding using a first joining device 54 (FIG. 4); afirst conveyance step of supporting the first sheet-shaped member 56 bythe resin frame member 24, and conveying the supported firstsheet-shaped member 56 to a second joining device 60 (hereinafterreferred to as a “pressure bonding device 60”) (FIG. 5); a secondconveyance step of conveying a second electrode (the anode 20 in thepresent embodiment), which is the other electrode of the resin frameequipped MEA 10, to the pressure bonding device 60; and a second joiningstep (hereinafter also referred to as a “pressure bonding step”) ofjoining the first electrode and the second electrode together bythermocompression-bonding using the pressure bonding device 60.

In the first joining step, a frame member material sheet 50 containing aplurality of resin frame members 24, for example, is used as shown inFIGS. 3A and 3B. Specifically, the frame member material sheet 50 is astrip-shaped member containing a plurality of resin frame members 24serially arranged thereon as shown in FIG. 3B. A plurality of openings24 e each defining the inner end 24 ae of the resin frame member 24 arespaced from each other (i.e., arranged at intervals) in the lengthdirection of the frame member material sheet 50.

The frame member material sheet 50 is reeled out from a roll 52 (a firstroll) and fed to the first joining device 54 (FIG. 4), at which thefirst joining step is performed. In the roll 52, the frame membermaterial sheet 50 and a non-illustrated interlayer film (a protectionfilm) are laminated and wound into a roll. As the frame member materialsheet 50 is reeled out from the roll 52, the inter-layer film is alsoreeled out. The reeled-out interlayer film is rewound on a wind-up roll(not shown). The frame member material sheet 50 is fed to the firstjoining device 54 of FIG. 4 in a state that a surface of the framemember material sheet 50 on which the adhesive layer 24 c (FIG. 2) isprovided is oriented upward.

As shown in FIG. 4, the first joining device 54 is fed with arectangular first sheet-shaped member 56 having the cathode 22 and theelectrolyte membrane 18 thereon. The first sheet-shaped member 56 has afirst supporting sheet 58, the cathode 22 supported on the firstsupporting sheet 58, and the electrolyte membrane 18 with the cathode 22provided on one surface thereof. The first supporting sheet 58 is madeof carbon paper, for example.

For example, a roll of a strip-shaped, multi-layered sheet composed ofthe first supporting sheet 58, the cathode 22, and the electrolytemembrane 18 (hereinafter referred to as a “second roll”) is used. Themulti-layered sheet is reeled out from the second roll. Then, by cuttingthe reeled-out multi-layered sheet at predetermined intervals with acutter (for example, a roller cutter), the rectangular firstsheet-shaped member 56 having predetermined dimensions is obtained.

The first sheet-shaped member 56 is fed to the first joining device 54with the electrolyte membrane 18 oriented downward, and placed on theresin frame member 24 (the frame member material sheet 50) (a firstsheet-shaped member placement step). In this case, the firstsheet-shaped member 56 is placed on the resin frame member 24 so thatthe electrolyte membrane 18 faces the opening 24 e of the resin framemember 24 and that the outer peripheral portion 18 c of the electrolytemembrane 18 overlaps the inner peripheral portion 25 of the resin framemember 24 over the entire circumference.

In the first joining step, the first sheet-shaped member 56 and theresin frame member 24 are thermocompression bonded with each other suchthat the outer peripheral portion 18 c of the electrolyte membrane 18 isjoined to the inner peripheral portion 25 of the resin frame member 24on a first surface 24 s 1 (the surface on which the adhesive layer 24 cis provided) over the entire circumference. Specifically, in the firstjoining step, a portion where the outer peripheral portion 18 c of theelectrolyte membrane 18 overlaps the inner peripheral portion 25 of theresin frame member 24 is clamped and thermocompression bonded (heatedand pressed) from above and below using the first joining device 54 withframe-shaped molds (an upper mold 54 a and a lower mold 54 b) whichconform to the shape of the outer peripheral portion 22 c of the cathode22.

Thermocompression bonding of the first sheet-shaped member 56 and theresin frame member 24 in the first joining step only has to produce ajoining force enough for preventing movement of the first sheet-shapedmember 56 relative to the resin frame member 24 until start of thepressure bonding step (the second joining step) after the first joiningstep. That is, the thermocompression bonding in the first joining stepis temporary pressure bonding (temporary fixing) for relatively weaklyjoining the first sheet-shaped member 56 and the resin frame member 24to each other. A thermocompression temperature in the first joining stepmay be in the range of 90° C. to 110° C., for example, and the pressingtime is several seconds.

An apparatus 74 for producing the resin frame equipped MEA 10 shown inFIG. 5 includes a first conveying device 76 that conveys the firstsheet-shaped member 56 and the resin frame member 24, a second conveyingdevice 61 that conveys the anode 20, and the pressure bonding device 60(the second joining device) that integrates the cathode 22 and the anode20 together by thermocompression bonding.

The first conveying device 76 performs the first conveyance step ofsupporting the first sheet-shaped member 56 by the resin frame member 24and linearly conveying the supported first sheet-shaped member 56 to thepressure bonding device 60. In FIG. 5, the first sheet-shaped member 56is an integrated component formed by integrating the member 56 with theresin frame member 24 (the frame member material sheet 50) in the abovefirst joining step, and is conveyed in the direction of arrow X.

The second conveying device 61 includes a rotary table 62 as a workpieceholding fixture, and performs the second conveyance step in which theanode 20 is conveyed to the pressure bonding device 60 by way of therotary table 62. The rotary table 62 is configured to rotate in thedirection of arrow R about a vertical axis of rotation a. A transferdevice 78 is installed near the rotary table 62 for transferring asecond sheet-shaped member 72 having the anode 20 thereon to the rotarytable 62.

As shown in FIG. 6, in the second sheet-shaped member 72, the anode 20is laminated on a second supporting sheet 70. The second supportingsheet 70 is made of carbon paper, for example. The second sheet-shapedmember 72 is cut off from a roll of a strip-shaped, multi-layered sheetcomposed of the second supporting sheet 70 and the anode 20 (hereinafterreferred to as a “third roll”). Specifically, the multi-layered sheet isreeled out from the third roll. Then, the reeled-out multi-layered sheetis cut off at predetermined intervals with an unillustrated cutter (forexample, a roller cutter). Thus, the rectangular second sheet-shapedmember 72 having predetermined dimensions is obtained.

In FIG. 5, the second sheet-shaped member 72 after being cut istransferred to the rotary table 62 at a transfer position P1 by thetransfer device 78. Specifically, the second sheet-shaped member 72 isplaced on a cushion pad 68 positioned on the rotary table 62 such thatthe anode 20 is oriented upward (a second sheet-shaped member placementstep). In this case, the second sheet-shaped member 72 is placed withina range of a hole 66 in plan view. The second sheet-shaped member 72will not fall into the hole 66 because it is supported on the cushionpad 68. Then, with rotation of the rotary table 62 in the direction ofarrow R, the second sheet-shaped member 72 is conveyed to a pressurebonding position P2 established inside the pressure bonding device 60.

As shown in FIG. 6, the rotary table 62 has a rectangular workpieceholding groove 63 (a workpiece placement portion) having a supportingsurface 63 a (a stepped portion), and the hole 66 adjacent to a lowerportion of the workpiece holding groove 63 and having a rectangularshape in plan view. As shown in FIG. 5, three or more workpiece holdinggrooves 63 are formed at angular intervals (four at 90° intervals in theillustrated example) about the axis of rotation a of the rotary table62.

As shown in FIG. 6, the rectangular cushion pad 68 (a supporting pad),which have larger outer dimensions than those of the hole 66, is placedon each supporting surface 63 a so as to cover the hole 66. The hole 66is opened at a lower surface 62 b of the rotary table 62. Preferably, agroove for positioning the second sheet-shaped member 72 is formed inthe upper surface of the cushion pad 68.

The first sheet-shaped member 56 and the resin frame member 24 afterhaving been joined together in the first joining step (hereinafterreferred to as an “intermediate joined component 59”) is fed to thepressure bonding position P2 within the pressure bonding device 60. Thepressure bonding device 60 has an upper mold 64 a and a lower mold 64 bfor clamping the intermediate joined component 59 and the anode 20 fromabove and below, and heating and pressing the intermediate joinedcomponent 59 and the anode 20 from above and below. Since a part of therotary table 62 is located within the pressure bonding device 60 (thesecond joining device) during thermocompression bonding of the anode 20and the resin frame member 24, the rotary table 62 may be regarded as apart of the pressure bonding device 60. Instead of the rotary table 62,a non-rotating table may be provided as a workpiece holding fixture.

The upper mold 64 a and the lower mold 64 b are spaced from each otherin the vertical direction so as to face each other across the workpieceholding groove 63, and are configured to be moved in the verticaldirection. The lower mold 64 b is inserted into the hole 66 of therotary table 62. The opening dimensions of the hole 66 and the outerdimensions of a pressing surface 65 b of the lower mold 64 b are largerthan the outer dimensions of the first sheet-shaped member 56 (thecathode 22 and the electrolyte membrane 18) and the outer dimensions ofthe second sheet-shaped member 72. The outer dimensions of a pressingsurface 65 a of the upper mold 64 a are larger than the opening 24 e ofthe resin frame member 24 and slightly smaller than the outer dimensionsof the first sheet-shaped member 56.

At the pressure bonding position P2, the intermediate joined component59 (the first sheet-shaped member 56 and the resin frame member 24)obtained in the first joining step is placed on the second sheet-shapedmember 72. In this case, the intermediate joined component 59 is placedon the second sheet-shaped member 72 such that the anode 20 faces theopening 24 e of the resin frame member 24 and that the outer peripheralportion 20 c of the anode 20 overlaps the inner peripheral portion 25 ofthe resin frame member 24 on a second surface 24 s 2 over the entirecircumference. As a result of this, the outer peripheral portion of thefirst sheet-shaped member 56 (the outer peripheral portion 18 c of theelectrolyte membrane 18) overlaps the outer peripheral portion of thesecond sheet-shaped member 72 (the outer peripheral portion 20 c of theanode 20) via the inner peripheral portion 25 of the resin frame member24.

Then, in the pressure bonding step (the second joining step), the anode20 and the resin frame member 24 are thermocompression bonded to eachother such that the outer peripheral portion 20 c of the anode 20 andthe inner peripheral portion 25 of the resin frame member 24 on thesecond surface 24 s 2 are joined together over the entire circumference.Specifically, in the pressure bonding step, a portion where the outerperipheral portion 18 c of the electrolyte membrane 18, the innerperipheral portion 25 of the resin frame member 24, and the outerperipheral portion of the anode 20 overlap one another is clamped andthermocompression bonded (heated and pressed) from above and below bythe upper mold 64 a and the lower mold 64 b of the pressure bondingdevice 60. In this case, in the pressure bonding step, the cathode 22and the anode 20 are thermocompression bonded to each other via theopening 24 e of the resin frame member 24.

In the pressure bonding step, the MEA 10 a (FIG. 2) in which the cathode22 and the anode 20 are positioned on both sides of the electrolytemembrane 18 is obtained, and an integrated component in which the resinframe member 24 (the frame member material sheet 50) is joined to andintegrated with the outer peripheral portion of the MEA 10 a isobtained.

The thermocompression bonding in the pressure bonding step is mainpressure bonding for firmly joining the intermediate joined component 59and the second sheet-shaped member 72 together in order to obtain astate in which the resin frame member 24 is integrated with the outerperipheral portion of the MEA 10 a. Thus, the strength of joining by thethermocompression bonding in the pressure bonding step is higher thanthe strength of joining by the thermocompression bonding in the firstjoining step. The thermocompression temperature in the pressure bondingstep is in the range of 160° C. to 180° C., for example. The pressingtime in the pressure bonding step is preferably longer than the pressingtime in the first joining step described above.

After the pressure bonding step, the frame member material sheet 50integrated with the MEA 10 a is cut into a rectangular shape havingpredetermined dimensions, thereby obtaining the resin frame equipped MEA10 shown in FIG. 1.

In this case, the method for producing the resin frame equipped MEA 10according to the present embodiment provides the following effects.

The method for producing the resin frame equipped MEA 10 includes thefirst conveyance step of supporting the first sheet-shaped member 56having the cathode 22 and the electrolyte membrane 18 by the resin framemember 24, and linearly conveying the supported first sheet-shapedmember 56 to the pressure bonding device 60, the second conveyance stepof conveying the anode 20 to the pressure bonding device 60 by way ofthe rotary table 62, and the pressure bonding step of heating andpressing the cathode 22 and the anode 20 from above and below by thepressure bonding device 60 to thereby integrate the cathode 22 and theanode 20 together.

Thus, according to the method for producing the resin frame equipped MEA10, the cathode 22 and the electrolyte membrane 18 are linearly conveyedby way of the resin frame member 24, while the anode 20 is conveyed byway of the rotary table 62, and the cathode 22 and the anode 20 areintegrated together by pressure bonding in the pressure bonding device60. Thus, it is possible to efficiently produce the resin frame equippedMEA 10 including the MEA 10 a and the resin frame member 24 joined tothe outer peripheral portion of the MEA 10 a, wherein the MEA 10 acomprises the electrolyte membrane 18, and the cathode 22 and the anode20 sandwiching the electrolyte membrane 18 therebetween.

In the first conveyance step, a plurality of first sheet-shaped members56 are conveyed in the form of a strip-shaped frame member materialsheet 50 containing a plurality of resin frame members 24 (i.e.,conveyed by the strip-shaped frame member material sheet 50). With thisstructure, the frame member material sheet 50 extending in the form of astrip is intermittently moved, whereby the plurality of firstsheet-shaped members 56 can be sequentially conveyed to the pressurebonding device 60. Thus, it is possible to more efficiently produce theresin frame equipped MEA 10.

As shown in FIG. 5, the rotary table 62 has, about the axis of rotation,three or more workpiece holding grooves 63 on which the anode 20 can beplaced. With this structure, it is possible to carry out an additionalstep at a midway position (a first intermediate position P3) from thetransfer position P1 to the pressure bonding position P2 along therotation direction of the rotary table 62 or at a midway position (asecond intermediate position P4) from the pressure bonding position P2to the transfer position P1 along the rotation direction of the rotarytable 62. By carrying out the additional step at the first intermediateposition P3 or the second intermediate position P4, space can beeffectively utilized.

In this case, at the first intermediate position P3, cleaning (such asair blowing) of the anode 20 on the way to the pressure bonding device60 may be carried out as the additional step, for example. At the secondintermediate position P4, cleaning (such as air blowing) of one (orboth) of the workpiece holding groove 63 and the cushion pad 68 thathave left the pressure bonding device 60 may be carried out as theadditional step, for example.

In the present embodiment, four workpiece holding grooves 63 areprovided at angular intervals of 90° on the rotary table 62. Thus, oneanode 20 corresponding to one product can be reliably conveyed at eachof the angular intervals of 90°. Owing to conveying of one anode at eachof the 90° intervals, it is possible to perform conveyance in a shorterperiod of time.

The method for producing the resin frame equipped MEA 10 includes thefirst joining step (FIG. 4) of thermocompression-bonding the firstsheet-shaped member 56 having the cathode 22 and the electrolytemembrane 18 to the resin frame member 24 with the adhesive layer 24 cprovided on the first surface 24 s 1 so that the outer peripheralportion of the first sheet-shaped member 56 and the inner peripheralportion 25 of the resin frame member 24 on the first surface 24 s 1 arejoined together, and the second joining step (FIG. 6) ofthermocompression-bonding the anode 20 to the resin frame member 24 sothat the outer peripheral portion of the anode 20 and the innerperipheral portion 25 of the resin frame member 24 on the second surface24 s 2 are joined together.

Thus, according to the method for producing the resin frame equipped MEA10, the first joining step of thermocompression-bonding the firstsheet-shaped member 56 having the electrolyte membrane 18 and thecathode 22 to the resin frame member 24, and the second joining step ofthermocompression-bonding the resin frame member 24 to the anode 20 areperformed, rather than integrating the electrolyte membrane 18, thecathode 22, the anode 20, and the resin frame member 24 together in asingle thermocompression-bonding process. Thus, it is possible toefficiently produce the resin frame equipped MEA 10 including the MEA 10a and the resin frame member 24 joined to the outer peripheral portionof the MEA 10 a, the MEA 10 a comprising the electrolyte membrane 18,and the cathode 22 and the anode 20 sandwiching the electrolyte membrane18 therebetween.

The thermocompression temperature in the second joining step is higherthan the thermocompression temperature in the first joining step.Accordingly, simple thermocompression-bonding is enough in the firstjoining step. Thus, it is possible to reduce the time required for thefirst joining step, and to obtain sufficient joining strength in thesecond joining step.

In the first joining step, the electrolyte membrane 18 (the firstsheet-shaped member 56) having the cathode 22 provided on one surfacethereof is thermocompression-bonded to the frame member material sheet50 containing a plurality of resin frame members 24 (FIGS. 3A and 3B).With this structure, it is possible to continuously convey the firstsheet-shaped member 56 to the second joining step (the pressure bondingdevice 60 or the second joining device), and thus it is possible toproduce the resin frame equipped MEA 10 more efficiently.

In the second joining step, thermocompression-bonding is performed fromabove and below in a state in which the resin frame member 24 joined tothe first sheet-shaped member 56 (the intermediate joined component 59)is stacked on the anode 20. Thus, by placing the anode 20 on a table(the rotary table 62) and stacking the resin frame member 24 joined tothe first sheet-shaped member 56 on the anode 20,thermocompression-bonding can be performed in a state that the resinframe member 24 and the anode 20 are accurately and easily positionedand aligned with each other.

The first sheet-shaped member 56 may have the anode 20 thereon insteadof the cathode 22, and the second sheet-shaped member 72 may have thecathode 22 thereon instead of the anode 20. In this case, in the firstjoining step, the outer peripheral portion 18 c of the electrolytemembrane 18 having the anode 20 provided on one surface thereof isjoined to the inner peripheral portion 25 of the resin frame member 24on the first surface 24 s 1 by thermocompression. In the pressurebonding step, the outer peripheral portion 22 c of the cathode 22 isjoined to the inner peripheral portion 25 of the resin frame member 24on the second surface 24 s 2 by thermocompression.

The present embodiment a cooling structure on a cell-by-cell basis wherecells each formed by sandwiching one MEA between two separators arestacked together, and the coolant flows between the adjacent cells.Alternatively, a so-called skip cooling structure where coolant flows atintervals of every predetermined number of cells may be adopted. In sucha case, each of the cells includes three or more separators and two ormore MEAs.

The present invention is not limited to the above-described embodimentbut various modifications are possible without departing from the scopeof the present invention.

What is claimed is:
 1. A method for producing a resin frame equippedmembrane electrode assembly, the method comprising: a first joining stepof thermocompression-bonding a sheet-shaped member including a firstelectrode and an electrolyte membrane with the first electrode providedon one surface thereof to a resin frame member having an opening and anadhesive layer provided on one surface thereof so that an outerperipheral portion of the sheet-shaped member and an inner peripheralportion of the resin frame member on the one surface are joinedtogether; and a second joining step of thermocompression-bonding asecond electrode to the resin frame member so that an outer peripheralportion of the second electrode and an inner peripheral portion of theresin frame member on another surface thereof are joined together. 2.The method for producing the resin frame equipped membrane electrodeassembly according to claim 1, wherein a thermocompression temperaturein the second joining step is higher than a thermocompressiontemperature in the first joining step.
 3. The method for producing theresin frame equipped membrane electrode assembly according to claim 1,wherein in the second joining step, the first electrode and the secondelectrode are thermocompression-bonded to each other in the opening withthe electrolyte membrane being interposed therebetween.
 4. The methodfor producing the resin frame equipped membrane electrode assemblyaccording to claim 1, wherein in the first joining step, a portion wherean outer peripheral portion of the electrolyte membrane overlaps theinner peripheral portion of the resin frame member is clamped andthermocompression-bonded from above and below using frame-shaped moldsconfigured to conform to a shape of an outer peripheral portion of thefirst electrode.
 5. The method for producing the resin frame equippedmembrane electrode assembly according to claim 1, wherein in the firstjoining step, the electrolyte membrane is thermocompression-bonded to aframe member material sheet containing a plurality of the resin framemembers.
 6. The method for producing the resin frame equipped membraneelectrode assembly according to claim 1, wherein in the second joiningstep, thermocompression-bonding is performed in a state in which theresin frame member joined to the sheet-shaped member is stacked on thesecond electrode.